This invention relates to integrated circuit chip testing, and more particularly to a test jig apparatus for holding and aligning an integrated circuit chip.
After an integrated circuit (IC) is fabricated, the IC may be tested to determine whether the IC is functional and whether it operates within product specifications. A test jig apparatus is typically provided to receive and align the IC for testing purposes. The IC leads can be pressed against test pads connected to a circuit tester, using a workpress that reciprocatingly urges the IC leads and the test pads together.
As the workpress moves back and forth, an electrostatic charge can develop within the test jig apparatus. If this electric charge flows through the IC by electrostatic discharge (ESD), the resulting current can physically damage the IC held by the test jig apparatus. For example, ESD from accumulated charge on an IC test jig workpress can discharge several microcoulombs (equivalent to more than 10.sup.13 free electrons) on an adjacent IC chip, thus destroying or disabling the chip. The problem of ESD appears to worsen for operation at higher temperatures, e.g. T.gtoreq.125.degree. C.
FIG. 1 illustrates operation of a test jig apparatus 11 from the prior art. The test jig apparatus 11 is of a one-piece construction, including a base 13 with a central aperture 15 (optional) therein, the base 13 having a substantially rectangular top surface 14 with approximately the same shape and planar dimensions as an IC chip 21 to be tested. The test jig apparatus 11 also has four side flanges 17A, 17B, 17C and 17D rigidly extending from the base 13 to form a "cup" to receive and hold the IC chip 21 for testing. The base 13 and four side flanges 17A, 17B, 17C and 17D together form a one-piece construction and are made of a non-electrically conductive material such as VESPULE. An IC chip 21 is received by this "cup" and is further aligned so that the IC leads 23 mate with test pads (not shown) connected to electronic equipment (not shown) that will be used to test the IC chip.
Because the material from which the base and side flanges is made is electrically non-conductive, static charge that accumulates on test jig 11 may discharge through the IC chip being tested in the test jig apparatus. This can damage or destroy the IC chip. Furthermore, accumulated electrical charge on the test jig apparatus 11 may destroy or damage the test jig apparatus itself, requiring that the entire test jig apparatus be replaced.
What is needed is a test jig apparatus that: (1) can operate reliably over a long term at temperatures exceeding 125.degree. C.; (2) allows replacement of damaged portions of the test jig apparatus without requiting replacement of the entire test jig apparatus; and (3) resists electric charge build-up and subsequent electrostatic discharge during operation of the apparatus.